Detection method of a position pierced by a single-tip optical fibre probe in bubble measurement

Mizushima, Yuki; Saito, Takayuki

doi:10.1088/0957-0233/23/8/085308

Cited by 18 publications

(9 citation statements)

References 27 publications

(9 reference statements)

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“…The reason why measuring foam and foam cells is so difficult is that it requires the measurement of thin liquid films. A different measurement technique for thin liquid-film flow was proposed by Mitsuhashi and Saito (2010), the measurement technique, however, is not able to be applied to the foam measurement.…”

Section: Some Numerical Simulation Results Illustrating Howmentioning

confidence: 99%

Improvement of Optical Fiber Probing in Multiphase Systems, and the Possibility of Practical Application in Chemical Engineering Processes

Saito

Sato

Nihei

et al. 2018

J. Chem. Eng. Japan / JCEJ

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Optical ber probing (OFP) is a very useful and practical technique for investigating and monitoring multiphase systems, and it is particularly suitable for simultaneously measuring a bubble's/droplet's chord length, velocity and number density in an industrial-scale apparatus, as well as a laboratory-scale setup. Here, we outline the principles of OFP and propose several types of optical ber probes that meet the requirements for particular purposes of the multiphase systems in chemical engineering processes. We describe measurement methods that use an optical ber probe suitably tuned for liquid lm and foam, as well as for bubble measurement. The basic measurement principle of OFP is very simple: the probe tip's detection of changes in the refraction indices from a gas phase to a liquid phase or vice versa. For example, to precisely measure a bubble's properties such as the chord length and velocity, it is necessary to determine the precise relationship between the process of the optical ber probe's penetration into the bubble and the optical signal. Since the probing signal provides a variety of information due to the complicated interaction of the laser beams, optical ber and gas-liquid interfaces, it is necessary to use both experimental and computational approaches in order to extract the physical meanings of the probe's signals. Using our own fully-3D ray-tracing simulator and well-arranged high-speed visualization setups, we discuss how to improve the measurement accuracy of OFP. We rst computationally analyze the OFP signals under several penetration conditions, and we explain our recommendations regarding how to improve the accuracy of a single-tip optical ber probe used for measurement in multiphase systems. On the basis of our present ndings and the improvement in measurement accuracy, we then propose several applications of OFP to chemical engineering processes.

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Section: Some Numerical Simulation Results Illustrating Howmentioning

confidence: 99%

Improvement of Optical Fiber Probing in Multiphase Systems, and the Possibility of Practical Application in Chemical Engineering Processes

Saito

Sato

Nihei

et al. 2018

J. Chem. Eng. Japan / JCEJ

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“…Asymmetrical deformation was quantitatively discussed by Vejražka et al; a horizontal shrinking of a bubble is observed while touching the probe (Vejražka et al 2010). Additionally, bubbles behave unexpectedly due to their zigzag/helix motion, which is touching the probe (Mizushima and Saito 2012). Consequently, although the pre-signal intensity appears to be large, the bubble motion might be undesirable (Fig.…”

Section: Accuracy Of the Chordlength Measurementmentioning

confidence: 90%

“…The amplitude of the pre-signal becomes the largest, only when the S-TOP pierces a bubble normally and at its center region. Hence, applying this particular characteristic, the touch position/angle can be detected (Mizushima and Saito 2012).…”

Section: Pre-signal Threshold Methodmentioning

confidence: 99%

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Measurement technique of bubble velocity and diameter in a bubble column via single-tip optical-fiber probing with judgment of the pierced position and angle

Mizushima

Sakamoto

Saito

2013

Chemical Engineering Science

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Our objective is to improve the accuracy of bubble measurement with Single-Tip Optical fiber Probe (S-TOP) in a bubbly flow. The STOP measures a point-wise void fraction and a velocity and diameter of a bubble simultaneously, by using only a single Mizushima, Sakamoto, and Saito CES 2 wedge-shaped tip. The STOP structure is very simple but raises an issue of an unclear touch position/angle between the STOP and a bubble. We propose a pre-signal threshold method in order to solve this issue. The pre-signal is one of the noisy optical signals from the STOP. First, the STOP signals are quantitatively analyzed with a newly developed 3D computational ray tracing method; the simulator can trace enormous ray segment trajectories in an optical fiber and render complicated optical boundary conditions. Moreover, in the simulator, evaluation of the complex output signals is achieved by computing the polarization and energy of every ray. We discovered that the intensity of the pre-signal indicates whether the STOP touches normally the center region of the bubble, or does not. We applied this characteristic to practical STOP measurement of a bubbly flow. As a result, the difference between the measured chord length via the STOP and the bubble minor axis from visualized images was significantly improved from 42 % (existing signal process) to 15 % (with processing through the method).

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“…Subsequently, Cartellier and Barrau improved the reproducibility of the sensor shape by chemically etching the OFP sensor using an acid. 20,21 Mizushima and Saito 22 fabricated a wedge-shaped sensor by grinding the stretched OFP sensor at an angle of 35 to the sensor axis, thereby maximizing the change in the intensity of the electrical signal when the sensor passes the phase interface. They showed that because of the curvature of the bubble interface, the signal gradient varies depending on where the sensor makes contact.…”

Section: Introductionmentioning

confidence: 99%

Measuring local droplet parameters using single optical fiber probe

et al. 2019

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This article proposes a new single optical fiber probe (OFP) sensor method for measuring local droplet parameters such as droplet fraction, droplet velocity, and droplet diameter. To this end, we developed a stretched conical optical fiber probe (SC-OFP) sensor that minimizes the wetting of the sensing tip at a high droplet velocity, a discrimination algorithm based on the first and second derivatives of the output of the raw signal of the OFP sensor, and a method that uses neural network training to determine local droplet velocity independently of droplet size. In the experiments conducted, the developed SC-OFP sensor measured local droplet velocity with a mean absolute percentage error (MAPE) smaller than 4.1% for velocities ranging from 2 to 32 m/s, and droplet diameter with a MAPE smaller than 4.9% for diameters ranging from 0.29 to 1.78 mm.

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Detection method of a position pierced by a single-tip optical fibre probe in bubble measurement

Cited by 18 publications

References 27 publications

Improvement of Optical Fiber Probing in Multiphase Systems, and the Possibility of Practical Application in Chemical Engineering Processes

Improvement of Optical Fiber Probing in Multiphase Systems, and the Possibility of Practical Application in Chemical Engineering Processes

Measurement technique of bubble velocity and diameter in a bubble column via single-tip optical-fiber probing with judgment of the pierced position and angle

Measuring local droplet parameters using single optical fiber probe

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